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61  Using Arduino / Programming Questions / calculating error, quickest way on: December 22, 2012, 12:50:32 am
I've got a project wher the frequncy of a timer is changed from 1hz to 1mhz, using the 16 bit timer is fine for frequency below a few khz, however above that the frequency doesn't. Transistion smoothly and starts jumping a few values, one its above 300khz its jumping by tens, 400khz by hundreds, is there a way to instead of scrolling from say 400khz to 430khz manually by changing the number until the value is enough to actually cause a change, what would be an easier way to start jumping by the error so it goes from one correct value to the next, I know I can precalculate the error and use a lookup table but I imagine there has to be a simple formula to do the same since the error is the same every time and can be calculated easily
Any ideas?
62  Using Arduino / General Electronics / Re: managing current on: December 22, 2012, 12:41:02 am
It all depends on what you wanna spend, there thousands of mosfets out there, you could go all out with a mosfet driver and a large power mosfet, or just a cheap one driven off the arduino pin
63  Using Arduino / General Electronics / Re: Strange behavior on digital pins on: December 20, 2012, 06:47:44 pm
What makes you say a value less than 100k would fry the sensor? 10k I imagine would be a better number to use, and unless it really cand handle much current you could go lower than 1k
64  Using Arduino / General Electronics / Re: managing current on: December 20, 2012, 03:02:34 pm
Id maybe look around for a better fet, maybe get away without a heatsink if it matters, unless u have heatsinks laying aeound it'll be cheaper just to get a better mosfet
65  Using Arduino / General Electronics / Re: Strange behavior on digital pins on: December 20, 2012, 10:29:56 am
Probably because that input is floating, that makes it the most susceptible to noise, a pulldown or pullup resistor would fix that, easiest just use the internal pullup on the pin
66  Using Arduino / General Electronics / Re: managing current on: December 19, 2012, 11:40:19 pm
power dissapated is current squared multiplied by resistance and rds on at 4.5v is .05 so 10*10*.05 is 5w
And I get that because P=IV, V=IR so P=I(IR) or P=I^2*R
67  Using Arduino / General Electronics / Re: managing current on: December 19, 2012, 11:02:34 pm
@10 ur gonna have atleast 5W heat so definetly need a heatsink,
68  Using Arduino / General Electronics / Re: managing current on: December 19, 2012, 09:21:24 pm
Especially for the higher current led strings, the easiest way is a logic level n-channel power mosfet with a 220 ohm resistor on the gate
69  Using Arduino / General Electronics / Re: Remote Tree on: December 19, 2012, 04:29:55 pm
Why not add a motion sensing device that turns the tree on when your in the room? If nobody is there to see it why leave it on?
70  Using Arduino / Microcontrollers / Re: attiny 85, any pointers?/ on: December 19, 2012, 04:16:13 pm
For my situation with the 85, it worked fin because all I need is cs to be a dedicated pin, the rest are multipurposed for other things, and I used it on 8mhz
71  Using Arduino / Microcontrollers / Re: attiny 85, any pointers?/ on: December 19, 2012, 12:34:51 pm
Np, let me know if u figure it out, feels good to know something I made works for other people too lol
72  Using Arduino / Microcontrollers / Re: attiny 85, any pointers?/ on: December 19, 2012, 09:52:26 am
Does anything change when you force the definitions?
73  Using Arduino / Microcontrollers / Re: attiny 85, any pointers?/ on: December 18, 2012, 05:48:22 pm
Just change the core name to whichever yours is, youll find the name within the attiny core itself, I found it I think by pin definitions, then it will automatically recognize it
74  Using Arduino / Microcontrollers / Re: attiny 85, any pointers?/ on: December 18, 2012, 04:19:50 pm
In the library I included a define for the 84, perhaps depending on your method of enabling attiny use on arduino because I based it on the third party source that I used, I believe there are 2-3 different ones, perhaps that's the fault, ill try on an 84 when I get the chance, tho I think someone else said it worked on an 84
75  Using Arduino / General Electronics / Re: A Cautionary Capacitor Tale on: December 16, 2012, 07:57:29 pm
Lol this is quite interesting, thanks for bringing it up, I just designed something and I had to calculate a capacitor for a boostrapping circuit, and now I'm hoping it works since I used a 0805 2.2uf cap, atleast now if I have problems with that ill know where to look, and maybe ill just automatially stack an extra cap on there, because it seems I will definetly have some sort of drop
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